Cases for hard cover books are typically produced by printing a rectangular sheet of paper, cloth or leather, known as the cover material, and subsequently gluing the cover material to a pair of panels and a spine. The panels and spine (the rigid component) provide rigidity for the case, with one of the panels forming the front of the finished book and the second forming the back. The spine provides rigidity to the spine portion of the book. The spine and panels are typically made of chipboard or other stiff material. A space is usually left between the spine and the panels so that the cover may be opened and closed in hinge-like fashion. Manufacturing techniques typically include a step of placing the panels and spine on a glued cover material and then folding the edges of the cover material up and onto the inside edges of the panels (and the ends of the spine). Together, the spine, panels, and cover material are known as a hard book cover assembly.
In an unfinished hard book cover assembly, the cover material is sized and placed to extend outwardly past the periphery of the spine and the panels to be later folded back over the edges of the spine and panels to produce an attractive cover. The overlapping edges of the cover material are glued on the inside of the panels and spine, and these edges are generally hidden later in the book making process when paper or other material is glued over the interior of the hard book cover in a manner that overlaps, and thus hides, the edge of the cover material from a reader. Typically, only a few millimeters of cover material are visible around the inside edges when a hard cover book is completed. One of the steps involved in producing a cover for hard cover books is the folding of the corners of the extended cover material over the corners of the panels. Procedures for fabricating a hard cover book are described below and in co-owned U.S Pat. No. 6,379,094 (the '094 patent) which is hereby incorporated by reference in its entirety herein.
There are two main types of corner folding used to make hard cover books. One type of corner fold is known as an “edition corner” (also cut corner, standard corner, tucked corner or square corner). The second type is known as a “library corner.”
For edition corners, the cover material is typically cut into a rectangular shape that is about 1½ inches larger in each of the X and Y dimension than the desired finished (open and flat) book cover (case) size. When the cover material is affixed to the rigid components of the hard book cover assembly (for example, 2 panels and 1 spine) there typically is a cover material overhang of about ¾ inch around the outer edges of the rigid components. To remove excess cover material, the corners of the cover material typically are trimmed prior to affixing the cover material to the panels and spine. By eliminating this corner material, multiple layers of bunched cover material do not develop at the corners of the finished hard book cover assembly.
Cover material is often cut in a stack so that multiple pieces can be cut simultaneously in preparation for a run of many copies of the same hard book cover assembly. This is typically performed at a cutting station separate from the hard book cover assembly apparatus.
An identically sized triangular piece is cut from each of the four corners as the spine and panel will be placed square and centered on the cover material. Preferably, these cuts are made at a 45 degree angle to the longitudinal edges of the panels leaving an amount of cover material extending outwardly from each of the outer two corners (in a direction bisecting the 90 degree corner of the panel) of each panel a distance that will be equivalent to approximately 2 times the thickness of the panel material in the finished product. By knowing what the final size of the finished hard book cover assembly will be and by placing the rigid component squarely centered on the cover material, all four corners of the cover material can be cut equally to arrive at approximately the desired overhang. Often, however, slight variations in placement of the spine or panels can result in a corner overhang that is not equal to the desired 2 times panel thickness.
After the corners have been cut and an adhesive has been applied to the cover material, the spine and panels are placed on the cover material with the outer edges of the panels in parallel with the adjacent (closest) outer edges of the cover material. Each edge can be longitudinally folded over the panel to produce an edition corner that has only a small area of glued, overlapping cover material on the inside surface of each panel at the corner.
For a library corner, the corner of the cover material is not cut off, but is instead folded back over the corner of the panel prior to folding back the longitudinal edges of the cover material. This results in an extra layer of cover material on the inside of the panel.
Due to the ease with which books and manuscripts can be printed using modem technologies, such as digital printing, a need has developed for hard cover book making machines that can produce small numbers (tens or hundreds, for example) of hard covers for authors and publishers desiring hard covers for their works. Furthermore, as digital printing becomes available in numerous outlets, including copy shops, work places, and even homes, there has developed a need for hard cover book making machines that can be operated in these areas. In addition to being inexpensive, it may be desired that the book cover making machines require as small an amount of space as possible, are easy to set up, and require minimal skill and training for operation. Space considerations may be of particular interest in those locations with higher real estate expense than traditional publishing companies.
In hard book cover making operations, it is desirable that a sheet of printed cover material be printed and cut accurately and with precision from one sheet to the next. In reality, this is not always the case, and often the printing may be out of registration, skewed or otherwise imperfect. Rectangular cover material is traditionally printed so that it can be centered in relation to the spine and panels, with a consistent amount of cover material overhang with respect to opposing edges. Often, the center of the cover material sheet is notched in the center at the top and/or bottom so that it can be easily aligned with the spine. If the printing on the cover material is not centered, or is not square, centering of the cover material in relation to the spine can result in a finished hard book cover assembly that is imperfect and may have to be discarded. For example, the title may not be aligned with the center of the spine on a finished book, or a photograph, border, or other artwork may extend inside the cover when originally designed to be displayed accurately on the outer portion of the cover. Such inaccuracies may not be discovered until after a number of imperfect cover assemblies are produced. This can result in, for example, added costs, significant downtime, or waste.